Efficacy and safety of dronedarone in patients with amiodarone-induced hyperthyroidism: a clinical study.

OBJECTIVE: The aim of the study was to examine the safety and efficacy of dronedarone in patients with a history of atrial fibrillation and amiodarone-induced hyperthyroidism. PATIENTS AND METHODS: We conducted a prospective study to evaluate the use of amiodarone and dronedarone in 124 patients with a history of paroxysmal atrial fibrillation who had no additional structural heart disease. All patients received amiodarone 200 mg qd. Out of 124 patients, 56 (45%) switched to dronedarone 400 mg bid due to amiodarone-induced hyperthyroidism and the remaining 68 patients (55%), with normal thyroid function, continued to receive amiodarone. The follow-up period was 12 months, and the patients were regularly monitored. RESULTS: The primary outcome after 6 months dronedarone and amiodarone group was 56 and 68, including 38 (68%) and 54 (79.4%) (Odds ratio [OR] = 1.17, 95% confidence interval [95% CI] = 0.68-2.02) patients with sinus rhythm (SR) and 18 (32.14%) and 14 (28.6%) (odds ratio [OR] = 0.64, confidence interval [95% CI] = 0.29-1.40) patients with atrial fibrillation (AF). The secondary outcome after 12 months showed significant difference in thyroid function in the dronedarone group. Out of 46 patients, 24 (56.18%) patients reduced hyperthyroidism compared to the amiodarone group; out of 68, 6 (8.9%) patients were observed to have hyperthyroidism. At 12 months, there were 24 (43%) and 22 (62%) (odds ratio [OR] = 0.75, confidence interval [95% CI] = 0.38-1.49) patients with SR, and 32 (57%) and 26 (38%) (odds ratio [OR] = 0.67, confidence interval [95% CI] = 0.36-1.25) patients with AF. CONCLUSIONS: In our study, dronedarone appears to be a good therapeutic option in the treatment of atrial fibrillation in patients with amiodarone-induced hyperthyroidism. However, long-term studies are needed to estimate the efficacy and toxicity of both drugs.